X-ray crystal structure studies will be undertaken on chemically-different drugs which have clinical use or potential as agents against central nervous system pathologies. The structures of a number of chemically-different compounds which have been reported to have anticonvulsant efficacies which make them potentially valuable clinical agents will be investigated. Comparisons of their three-dimensional sterochemistries with other useful antiepileptics will be made in order to derive information about the molecular determinants of biological activity. Structural investigations and comparisons will also be performed on dopamine analogues and antagonists, with the aim of understanding the stereochemical features responsible for dopaminergic activity and receptor binding. The structure of leucine-enkephaline, in a crystal form which contains at least four separate and independent molecules in the asymmetric unit, will be studied. In addition, crystallization attemps will be carried out on some active and inactive synthetic analogues of enkephalines in order to determine molecular bases of opiate and analgesic characteristics. We shall also continue attempts to utilize the knowledge we have so far gathered on anticonvulsant sterochemistry to design and synthesize new antiepileptic drugs.